Electrodeionization apparatus having geometric arrangement of ion exchange material

ABSTRACT

An electrodeionization apparatus adapted to remove ions from a liquid, the apparatus having a cathode proximate a first end of the apparatus and an anode proximate the opposite end of the apparatus and having a plurality of alternating diluting compartments and concentrating compartments positioned between the cathode and the anode, the diluting and concentrating compartments defined by anion and cation permeable membranes, and ion exchange material positioned within the diluting compartments, the diluting compartments having therein a continuous phase of a first ion exchange material containing a dispersed phase of clusters of a second ion exchange material. The method of removing ions from a liquid in such an electrodeionization apparatus comprises passing an aqueous liquid to be purified through the diluting compartments in which the diluting compartments have the continuous phase of a first ion exchange material with the dispersed phase of a second ion exchange material.

This application is a 371 of PCT/CA97/00018 filed Jan. 13, 1997.

FIELD OF INVENTION

This invention relates to an electrodeionization apparatus and a methodof removing ions from an aqueous liquid in an electrodeionizationapparatus and, more particularly, relates to an electrodeionizationapparatus having a plurality of diluting compartments and concentratingcompartments and a continuous phase of a first ion exchange materialwith a dispersed phase of a second ion exchange material, and a methodof removing ions from an aqueous liquid in such an electrodeionizationapparatus.

BACKGROUND OF THE INVENTION

The purification of liquid has become of great interest in manyindustries. In particular, pure water is used for many industrialpurposes rather than merely as drinking water. For example, pure wateris used in processes for producing semiconductor chips, in power plants,in the petrochemical industry and for many other purposes. Ion exchangeresins, reverse osmosis filtration and electrodialysis techniques havebeen used to reduce the concentration of ions in a liquid.

Electrodeionization apparatus have recently been used with morefrequency to reduce the concentration of ions in a liquid. The term"electrodeionization" generally refers to an apparatus and process forpurifying liquids which combine ion exchange resins, ion exchangemembranes and electricity to purify the liquids. An electrodeionizationmodule comprises alternating arrangements of cation permeable membranesand anion permeable membranes defining compartments therebetween. Inalternating compartments, there is provided ion exchange resin. Thosecompartments are known as diluting compartments.

The compartments which generally do not contain ion exchange resin areknown as the concentrating compartments. Ions migrate from the dilutingcompartments through ion exchange resin and ion permeable membranes intothe concentrating compartments by the introduction of current. Theliquid flowing through the concentrating compartments is discarded orpartially recycled and the purified liquid flowing through the dilutingcompartments is recovered as deionized liquid product.

U.S. Pat. No. 4,636,296 which issued Jan. 13, 1987 to Kunz discloses anapparatus and method for the demineralization of aqueous solutions. Anaqueous liquid is passed through alternating separate layers of cationexchange resin and anion exchange resin. This approach is cumbersome,electrode intensive and some distortion of the layers will likely occurduring service.

U.S. Pat. No. 5,308,467 which issued May 3, 1994 to Sugo et al.discloses an electrically regenerable demineralizing apparatus which hasa demineralizing compartment. Ion exchange groups are disposed onmonofilaments, woven fabric of monofilaments or nonwoven fabric ofmonofilaments by radiation-initiated graft polymerization. This ionexchange material is contained within the demineralizing compartment.

The use of such monofilaments in demineralizing apparatus is expensiveand, therefore, has not been readily accepted by purchasers of liquidpurification apparatus.

It is desirable to have an arrangement of ion exchange material in thediluting compartments of electrodeionization apparatus which does notuse monofilaments and which allows various types of ion exchangematerial to be arranged in the diluting compartment in non-layerarrangement but still allowing the liquid to be purified to come intocontact with discrete zones of two types of ion exchange material.

SUMMARY OF THE INVENTION

The disadvantages of the prior art may be overcome by providing anelectrodeionization apparatus which has a continuous phase of a firstion exchange material containing therein a dispersed phase of clustersof a second ion exchange material in the diluting compartments, and amethod of removing ions from an aqueous liquid in an electrodeionizationapparatus having such arrangement of ion exchange materials in thediluting compartments. This arrangement allows an increase in thethickness and size thereby permitting more resin to be placed in thediluting compartments and decreasing the number of membrane areasrequired for a corresponding increase in flow.

In its broad aspect, the ion exchange material of the inventioncomprises a porous and permeable ion exchanger containing cationexchange resin particles and anion exchange resin particles for use indeionizing an aqueous liquid including a porous and permeable continuousphase of one of cation exchange resin particles or anion exchange resinparticles and a porous and permeable dispersed phase of clusters of theother of the cation exchange resin particles or the anion exchange resinparticles within the continuous phase. The ion exchanger preferably isin the form of a shallow bed having opposite planar bed surfaces inwhich the dispersed phase clusters are conterminous with at least one ofthe planar bed surfaces. The dispersed phase clusters may extend throughthe shallow or thick bed and be conterminous with the opposite planarbed surfaces of the bed. The clusters can be shallow cylinders orellipses or transversely multi-faceted. The cation exchange resinparticles and the anion exchange resin particles preferably are bound bya binder polymer to form a cohesive bed.

More particularly, the electrodeionization apparatus adapted to removeions from an aqueous liquid includes a cathode in a cathode compartmentand an anode in an anode compartment and a plurality of alternatingdiluting compartments and concentrating compartments positioned betweenthe cathode and the anode, the diluting and concentrating compartmentsdefined by anion and cation permeable membranes, and porous andpermeable ion exchange material positioned within the dilutingcompartments, the porous and permeable ion exchange material comprisinga porous and permeable continuous phase of one of cation exchange resinparticles and anion exchange resin particles and a dispersed phase ofclusters of the other of the cation exchange resin particles and theanion exchange resin particles within the continuous phase. The ionexchanger preferably is in the form of a shallow bed or sheet havingopposite planar bed surfaces in which the dispersed phase clusters areconterminous with at least one of the planar bed surfaces. The dispersedphase clusters preferably extend through the shallow bed conterminouswith the opposite planar bed surfaces of the bed. The clusters can beshallow or elongated cylinders or ellipses, or transverselymulti-faceted such as elongated or shallow hexagons. The cation exchangeresin particles and the anion exchange resin particles preferably arebound by a binder polymer to form a cohesive bed, said bed filling thediluting compartment.

In a further aspect of the invention, the dispersed phase clusters ofcation or anion exchange resin particles are exposed with at least oneend conterminous with a planar surface of the bed for contacting theanion permeable membrane or the cation permeable membrane of the sametype, i.e., the clusters of cation exchange resin particles contact thecation permeable membrane, and the clusters of anion exchange resinparticles contact the anion permeable membrane, and preferably thedispersed phase clusters extend through the continuous phase and areconterminous the opposite planar surfaces of the continuous phase bedfor abutment and contact with both the anion permeable membrane and thecation permeable membrane, thereby bridging the diluting compartments.

In another aspect of the invention, the method of the invention forremoving ions from an aqueous liquid in an electrodeionization apparatuscompartment including an anode compartment having an anode and a cathodecompartment having a cathode, and a plurality of cation exchangemembranes and anion exchange membranes which are alternately arrangedbetween the anode compartment and the cathode compartment to formdemineralizing compartments each defined by an anion exchange membraneon the anode side and by a cation exchange membrane on the cathode side,and concentrating compartments each defined by a cation exchangemembrane on the anode side and by an anion exchange membrane on thecathode side, comprises feeding the aqueous liquid to be purifiedthrough the diluting compartments in which the diluting compartmentshave a continuous phase of a first ion exchange material with adispersed phase of clusters of a second ion exchange material, saidclusters of said dispersed phase being conterminous with and abutting atleast one of the anion and cation permeable membranes of the same sign,said clusters of the dispersed phase preferably extending through thecontinuous phase conterminous with and abutting both the anion andcation permeable members, flowing an electrical current between thecathode and the anode, and removing purified aqueous liquid from theapparatus.

A still further aspect of the invention comprises a method of producinga porous and permeable ion exchanger which comprises positioning atemplate having a planar cover plate with a plurality of shaped,thin-walled hollow elements having open top and bottom ends dependingdownwardly therefrom over a designated receiving area, and feeding anaqueous slurry of one of cation exchange resin particles or anionexchange resin particles to said template to form a continuous phase ofsaid ion exchange resin particles, and feeding an aqueous slurry of theother of the cation exchange resin particles or anion exchange resinparticles into the plurality of shaped, thin-walled hollow elements toform a plurality of dispersed phase clusters of the other of the cationexchange resin particles or the anion exchange resin particles.

Another aspect of the invention includes a method of producing a porousand permeable ion exchanger which comprises positioning an array ofdispensing nozzles for selectively dispensing an aqueous slurry ofcation exchange resin particles or anion exchange resin particles over adesignated receiving area, and feeding to said designated area anaqueous slurry of one of the cation exchange resin particles or theanion exchange resin particles to form a continuous phase of said ionexchange resin particles, and feeding an aqueous slurry of the other ofthe cation exchange resin particles or anion exchange resin particles ina predetermined pattern to form a plurality of dispersed discontinuousphase clusters of the other of the cation exchange resin particles orthe anion exchange resin particles. A further aspect of the inventioncomprises a method of producing a porous and permeable ion exchanger bydie cutting a plurality of shaped clusters of cation exchange resinparticles or anion exchange resin particles from a first sheet of saidresin particles to form a continuous phase of said ion exchange resinparticles having a plurality of holes therein, die cutting a pluralityof identical clusters of the other of cation exchange resin particles oranion resin particles from a second sheet of said resin particles, andfitting said cut-out clusters of the other of the cation exchange resinparticles or anion resin particles into the holes of the first sheet.

The ion exchanger can be formed over an ion exchange membrane forintimate contact of the dispersed phase of ion exchange particles withthe membrane, in a spacer frame or jig, and the ion exchanger frozen inthe spacer frame or jig for transfer.

The invention also includes the step of inserting a shaped mesh preformhaving a mesh size smaller than the average particles size into thehollow elements for incorporation into the discrete discontinuous phaseclusters or in the continuous phase of the ion exchange resin particles.

The shaped preform can have a right cylinder, or right rectangle, righthexagonal or right multi-faceted prismatic shape.

A honeycomb mesh can be incorporated in one of the dispersed phaseclusters or the continuous phase.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described with reference to theaccompanying drawings, in which:

FIG. 1 is a perspective view of a prior art electrodeionizationapparatus;

FIG. 2 is a fragmentary sectional view taken along line 2--2 of FIG. 1;

FIG. 3 is a perspective view of the arrangement of ion exchange materialof the invention;

FIG. 4 is a cross-sectional view taken along line 4--4 of FIG. 3; and

FIG. 5 is a perspective view of another arrangement of ion exchangematerial of the invention;

FIG. 6 is a perspective view of an apparatus for forming the ionexchanger of the invention; and

FIG. 7 is a side elevation of the apparatus shown in FIG. 6 mounted in acompartment spacer frame.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIG. 1, a prior art electrodeionization apparatus 10 isshown whereby ions may be removed from a liquid. In the preferredembodiment, ions such as sodium ion and chloride ion are removed fromwater.

The electrodeionization apparatus 10 has a rectangular frame 12. Theframe 12 comprises a rigid front plate 14 and a rigid back plate 16formed of metal. The front plate 14 and the back plate 16 are joinedtogether by a number of tie-bars or bolts 18. Each tie-bar 18 isinserted into a hole 20 located equispaced about the periphery of thefront plate 14 and inserted into corresponding holes 18a in back plate16. A cathode depicted by numeral 22 (FIG. 2) is located proximate thefront plate 14 in a cathode compartment 23 and an anode depicted bynumeral 24 is located proximate the back plate 16 in an anodecompartment 25. Openings 26 are located by the front plate 14 to allowliquid to enter the electrodeionization apparatus 10 for treatment.Insulating electrode block 28 forming an electrode compartment abuts theperimeter of the front plate 14 and insulating electrode block 30forming an electrode compartment continuously abuts the perimeter of theback plate 20. The electrodeionization apparatus 10 has a plurality ofalternating cation permeable membranes and anion permeable membranesdepicted by numeral 32 between the insulating electrode blocks 28 and30. The cation permeable membranes and anion permeable membranes 32define alternating concentrating and diluting compartments, to bedescribed.

FIG. 2 shows representative concentrating compartments 44, 46 and arepresentative diluting compartment 48, between the concentratingcompartments, in further detail. Cation permeable membranes 36 and 38and anion permeable membranes 40 and 42 define the concentratingcompartments and diluting compartments. Spacers (not shown) are placedbetween the membranes in the diluting compartments and concentratingcompartments. The spacers in the diluting compartments 48 have openingsfor placement of ion exchange material such as ion exchange resin beads49. It will be understood that ion exchange resin may also be placedwithin the concentrating compartments.

FIGS. 3 and 4 show a preferred arrangement of ion exchange material ofthe present invention to be used within the diluting compartment 48shown in FIG. 2. A bed 40 of porous and permeable continuous phase, i.e.matrix, of ion exchange material 50 has a plurality of spaced-apartcylinders of porous and permeable clusters of second ion exchangematerial 52, one of which is shown in FIG. 3, dispersed within matrix 50transversely of the bed plane. The ion exchange materials 50 and 52preferably are ion exchange resin particles in the form of beads. Theion exchange material 50 and ion exchange material 52 exchangeoppositely charged ions. For example, if continuous phase ion exchangematerial 50 is a cation exchange material, which will have fixednegative charges to capture cations, dispersed phase ion exchangematerial 52 is an anion exchange material which will have fixed positivecharges to capture anions. The transverse arrangement of clusters of thedispersed phased ion exchange material straddling or bridging thediluting compartments ensures that the aqueous liquid which flows withinthe diluting compartments 48 comes into contact with both forms of ionexchange resins to effectively exchange cations and anions.

Referring to FIGS. 1, 2, 3 and 4, aqueous liquid to be treated flowsthrough the openings 26 and through the concentrating compartments 44and 46 and the diluting compartment 48. Streams of liquid depicted byarrows 54 and 56 flow through the concentrating compartments 44 and 46respectively and a stream of liquid depicted by arrow 58 flows throughthe diluting compartment 48. The aqueous liquid contains ions such assodium and chloride ions.

Electric current flows between the cathode 22 in cathode compartment 23and the anode 24 in anode compartment 25. The current across cathode 22and anode 24 may be varied to control the overall efficiency of theelectrodeionization process.

As the liquid to be purified flows through the diluting compartment 48as depicted by arrow 58, it comes into contact with ion exchange resinbeads, as in the arrangement shown in FIGS. 3 and 4. Cation exchangeresin 50 has fixed negative charges and captures cations such as sodiumions present in the liquid. Anion exchange resin 52 has fixed positivecharges and captures anions such as chloride ions present in the liquid.As the ion exchange takes place between the liquid to be purified andthe cation exchange resin beads 50 and the anion exchange resin beads52, the voltage induces the non-desired cations and anions typified bysodium ions and chloride ions respectively to travel through membranes38 and 40 and into the adjacent concentrating compartments 46 and 44.The ion exchange resin is disposed in a transverse arrangement relativeto the flow of liquid as shown in FIGS. 3 and 4. This arrangementensures that most of the liquid flowing through the diluting compartment48 comes into contact with ion exchange material 50 and 52.

In the preferred embodiment, water is purified in theelectrodeionization apparatus 10. The current induces some splitting ofwater into hydrogen and hydroxyl ions. The hydrogen ions are transportedthrough the cation exchange resin 50 towards the cation exchangemembrane 38, and through cation exchange membrane 38 into theconcentrating compartment 46, as shown by arrows 66. The hydroxyl ionsare transported through the anion exchange resin 52, towards anionpermeable membrane 40, and through anion permeable membrane 40 into theconcentrating compartment 44, as shown by arrows 62. Thus, the ionexchange resin material 50 and ion exchange resin material 52 arecontinuously regenerated.

Anionic impurities, for example chloride ions in the water to bepurified in diluting chamber 48, are taken up by the anion exchangeresin material 52, by the usual ion exchange mechanism, and are thentransported along with hydroxyl ions through the anion exchange resin upto, and through anion permeable membrane 40, into concentratingcompartment 44 as shown by arrows 60. At the same time, an equivalentamount of hydrogen ions and impurity cations is transported from anadjacent diluting compartment into concentrating chamber 44, as shown byarrows 70.

Cationic impurities, for example sodium ions, in the water to bepurified in diluting chamber 48 are taken up by the cation exchangeresin material 50, by the usual ion exchange mechanism, and are thentransported along with the hydrogen ions through the cation exchangeresin up to, and through cation permeable membrane 38, intoconcentrating compartment 46 as shown by arrows 64. At the same time, anequivalent amount of hydroxyl ions and impurity anions is transportedfrom an adjacent diluting compartment into concentrating chamber 46, asshown by arrows 68.

The water flows through the concentrating compartments 44 and 46 to awaste tank (not shown) or is recycled. The purified water flowingthrough the diluting compartment 48 is recovered as product.

It is understood that the dispersed ion exchange cluster material 52 maybe of any geometric shape within the ion exchange matrix material 50,e.g. cylindrical, conical, frusto-conical or elliptical incross-section, or multi-faceted in cross-section such as hexagonal rightprismatic, to increase the surface area of the clusters.

FIG. 5 shows another embodiment of the arrangement of ion exchange resinmaterial 50 and 52 of the present invention within the dilutingcompartments of an electrodeionization apparatus in which the dispersedcluster phase 60 in cylindrical form is aligned transversely within thediluting compartment and is continuous with and contacts an ionpermeable membrane of the same charge, i.e. the same sign. For example,an anion exchange resin cluster 60 would be contiguous with and contactan anion permeable membrane 62. Preferably, the ion exchange clusters orislands extend through the continuous phase and are conterminous withthe opposite faces 64, 66 of the bed 49, as typified in FIG. 3, wherebythe dispersed clusters are contiguous with and will abut and contactboth the anion permeable membrane and the cation permeable membrane.

The cluster 50 may be formed from a shallow bed or sheet of a continuousphase of ion exchange resin particles of a first or second ion exchangematerial, bonded by a polymeric binder, by die cutting clusters of thedesired size and shape from the sheet.

A sheet of a continuous phase of ion exchange resin particles of an ionexchange material having an opposite charge bonded by a polymeric resinhaving a plurality of holes corresponding in size and shape to theclusters 50 die cut therefrom, can receive the cut-out clusters 50having the opposite charge in tight-fitting frictional engagement toform the ion exchangers. A thermoplastic polymeric binder such as a lowdensity polyethylene, linear low density polyethylene, or the like, inan amount sufficient to form a cohesive sheet or bed structure suitablefor handling, while retaining good porosity, liquid permeability and ionexchange capacity, can be used to form the starting sheets of the firstand second ion exchange material.

The porous and permeable ion exchangers can be formed in situ in thediluting compartments by the use of an array of dispensing nozzles toaccurately and efficiently deliver metered amounts of a first ionexchange material and amounts of a second ion exchange material, asslurries, to a diluting chamber frame or template to form the requiredpatterned configuration of a continuous phase of a first ion exchangematerial with a discontinuous phase of a second ion exchange material.The desired number of individual dispersed domains, e.g., cylindricalclusters of the second ion exchange material, can be formed directly.Individual dispersed domains of the second ion exchange material ofvarious shapes, such as cylindrical or hexagonal right prismatic,conical, frusto-conical, and the like, can be formed by varying thenumber, shape and position of the dispensing nozzles and by varying therate of delivery of the second ion exchange material in coordinationwith the delivery of the continuous phase of the first ion exchangematerial. The continuous phase of the first ion exchange material canreadily be formed with the use of a plurality of dispensing nozzles byvarying the number, size and geometric arrangement of these meteringnozzles, the relative amounts of ion exchange materials delivered by therespective nozzles, and by the relative rate of delivery. The meteringof ion exchange materials can be achieved by a number of means,including the use of screw feeders, displacement feeders, gravity, andthe like. The array of nozzles provides the desired pattern of ionexchange materials; however, it may consist of a subset thereof, theentire desired pattern being built up by changing the relative positionsof the assembly of dispensing nozzles and the diluting chamber frame ortemplate.

A patterned template can be used to accurately and efficiently deliverthe desired amounts of a first ion exchange material and of a second ionexchange material, as slurries, to form the required patternedconfiguration of a continuous phase of a first ion exchange materialwith a discontinuous phase of a second ion exchange material. An exampleof such a template for cylindrical domains is shown in FIGS. 6 and 7.Template 101, corresponding to the desired pattern, comprises aplurality of shaped, thin-walled, hollow, open-ended elements 102 suchas hollow cylinders defining the perimeter of the desired isolateddomains of the second ion exchange material depending downwardly from aplanar cover plate 103. Cover 103 defines the desired area of thecontinuous phase of the first ion exchange material. Feed tubes 104 forintroducing the first ion exchange material in the form of a slurry ofthe ion exchange material suspended in water and discharge tubes 105 forremoving excess water or other fluid used in transporting the first ionexchange material, project upwardly from cover plate 103. A perimeterwall 106 may, if desired, extend downwardly around the edge of template101 and a peripheral flange 107 may extend outwardly from the edge ofthe template coplanar with cover plate 103. In use, the template isplaced within a diluting compartment spacer frame 110 (FIG. 7) with wall106 seated on and in contact with an ion exchange membrane 111. Thefirst ion exchange material is sluiced into the template via feed tubes104 and discharge tubes 105, as indicated by arrows 112 and 113, therebyproviding the desired continuous phase of the first ion exchangematerial. An aqueous slurry of the second ion exchange material can beflooded onto the cover plate 103 to fill the tubes 102 with the secondion exchange material, excess ion exchange material being removed bymeans of a wiper by wiping off the excess second ion exchange materialflush with the cover plate 103 or by flooding the cover plate 103 withwater to rinse off excess solid material. Cover plate 103 may in turnhave a cover, not shown, spaced therefrom to form a shallow passagecoextensive with the width and length of cover plate 103 to direct theaqueous slurry uniformly across the cover plate 103 and avoidchannelling for uniform deposition of the second ion exchange materialin the domain tubes 102. The rate of filling of the tubes to form thediscontinuous phase domains can be controlled by varying the slurry flowrate and the slurry density.

The template 101 is then removed from the spacer frame 110, leaving thedesired pattern of continuous phase of first ion exchange material withdiscontinuous dispersed phase of clusters of second ion exchangematerial within the spacer frame.

The outwardly extending peripheral flange 107, seats on the uppersurface of spacer frame 110, thereby obviating the need for perimeterwall 106 to seat on ion exchange membrane 111 if preferred.

This procedure also can be carried out with the use of a working jig,not shown, in lieu of the diluting spacer frame 110. A jig frame seatedon a plastic film, with an embodiment of cover plate 103 seated thereon,can receive continuous and discontinuous phases of ion exchangeparticulate material having opposite charges by sluicing or floodingslurries of the ion exchange material into the respective cavities, asshown in FIGS. 6 and 7. Alternatively, a plurality of dispensing nozzlescan be used to form a desired patterned configuration of continuous anddiscontinuous phases in a jig. The bed comprised of the continuous anddiscontinuous phases can be transported to a site for packing into adiluting compartment.

The fabrication methods can be used to achieve patterns with differentlyshaped domains by altering the template accordingly. The presentfabrication methods can also be applied to making other patterns andconfigurations in which neither phase of material is continuous.

The required configuration of a continuous phase consisting of a firstion exchange material with a discontinuous phase of a second ionexchange material can be stabilized by means of a fine mesh defining therespective continuous and discontinuous regions. The openings in themesh permit the flow of the water to be treated. The openings in themesh are somewhat smaller than the ion exchange beads to be separated.Preferably, the relative sizes of the mesh openings and the ion exchangebeads is such that in the compacted state obtained in a dilutingchamber, the ion exchange beads on either side of the mesh come intocontact with each other. Deionization can also be obtained with finermesh where the ion exchange beads on either side of the mesh are inclose proximity, up to a few bead diameters, but do not touch.

Cylindrical preforms or thimbles of mesh can be placed inside thepatterned template described above in the area of the patterned templatecorresponding to the discontinuous phase. Following sluicing of the tworesins and removal of the template, the cylindrical mesh elements remainembedded in the resulting pattern of ion exchange material. A singlepreform or multiple preforms also can be placed in the area of thepatterned template corresponding to the continuous phase.

The ion exchange beads can be added selectively in a pattern by means ofdispensing nozzles as described above, the single preform or multiplepreforms occupying either or both of the continuous and discontinuousphases.

The fine mesh can be provided as individual preform cells or multipleinterconnected preform cells having a right circle, or right rectangle,hexagonal or the like right prismatic shape with individual cells havinga diameter or width of, for example, about 0.5 cm to fit into a discretecylindrical domains having a diameter of about 3 cm. A plurality ofinterconnected mesh cells having a honeycomb configuration 122 forming agenerally cylindrical domain 3 cm in diameter with individual cells of0.5 cm width filling the domains effectively constrains the ion exchangematerial within the domain becoming embedded in the domain, andfacilitates introduction of the ion exchange material by means ofdispensing nozzles.

An elongated fine-mesh honeycomb slab 124 having dimensions to fill thecompartment can be used for either or both the continuous anddiscontinuous phases to receive and stabilize the resin material fromnozzles.

Fine-mesh honeycomb preforms can be formed by cutting to a desired shapeand fitted into cylindrical holes in a patterned template and/or suchpreforms can be inserted into and comprise an integral part of thecontinuous phase of the template.

The required configuration of a continuous phase consisting of a firstion exchange material with a discontinuous phase of a second ionexchange material can be produced in a jig and frozen while wetted withwater for convenient handling during stack assembly in the frozen state.The required configuration also can be produced in a jig with an ionexchange membrane and/or with a concentrating or diluting spacer frameto yield a sub-assembly which can be conveniently handled during stackassembly in the frozen state. Once assembled, the stack is allowed tothaw yielding the desired patterned ion exchange materials, constrainedand stabilized in the diluting chambers.

It will be understood that these methods also can be used for formingpatterned ion exchange materials in concentrating and electrode spacerframes, as well as in non-electrochemical ion exchange devices.

The method and apparatus of the invention will now be described withreference to the following non-limitative example.

EXAMPLE 1 Exemplary Comparative Behaviour of Patterned Ion ExchangeMedium v. Mixed Bed ion Exchange Medium

Comparative experiments were conducted using an electrodeionizationapparatus with three diluting compartments. The apparatus consistedsequentially of: a 1.8 cm thick stainless steel end plate; a 2.5 cmthick PVC insulating electrode block; a platinum coated titanium anode;and approximately 0.1 cm thick electrode compartment spacer consistingof polypropylene mesh in an elastomeric frame, which frame served toseal the unit and to define fluid distribution ducts; an approximately0.07 cm thick cation permeable membrane; an approximately 0.1 cm thickconcentrating compartment spacer consisting of polypropylene mesh in anelastomeric frame, which frame served to seal the unit and to definefluid distribution ducts; three diluting/concentrating pairs in serieseach comprised of an approximately 0.07 cm thick anion permeablemembrane, an 0.8 cm thick diluting compartment consisting of an openpolypropylene frame for sealing and fluid distribution and forcontaining the ion exchange material to be evaluated, a fluiddistributor and a fluid collector equipped with strainer slots to retainion exchange beads in the diluting compartment, a 0.07 cm thick cationpermeable membrane, and an approximately 0.1 cm thick concentratingcompartment spacer; an approximately 0.07 cm thick cation permeablemembrane, an approximately 0.1 cm thick electrode compartment spacer, astainless steel cathode, a 2.5 cm thick PVC insulating electrode block,and a 1.8 cm thick stainless steel end plate. The dimensions of theworking area of the fluid compartments (electrode concentrating anddiluting) and the electrodes were 13 cm wide and 39 cm long in thedirection of fluid flow. The components of the electrodeionization stackwere held together in compression by 16×1.0 cm diameter threaded tierods positioned in holes around the perimeter of the stainless steel endplates.

In the usual manner, the apparatus was provided with fluid ducts,defined by openings, in the spacers and membranes, for the followingpurposes: to feed water to be purified to the diluting compartments; toremove purified water from the diluting compartments; to feed water tothe concentrating and electrode compartments; to remove water from theconcentrating compartments; and to remove water from the electrodecompartments. The water to be purified in the experiments consisted ofmunicipal drinking water which had been first filtered with activatedcarbon, softened with a sodium cation exchange unit, partially deionizedby reverse osmosis, and stored in a 800 gal polypropylene storage tank.This yielded feed water with a conductivity of approximately 3 μS/cm.The concentrating and electrode compartments were fed with filtered andsoftened water having a conductivity of about 350 μS/cm.

A first experiment was conducted in which the three dilutingcompartments were each filled with approximately 270 g of a boundintimate mixture, 50/50 by volume of dry Diaion strong acid and strongbase ion exchange resin, in the sodium and chloride forms. Theelectrodeionization stack was then regenerated by passing water to bepurified at flow rate of about 0.8 gpm through the dilutingcompartments, passing water through the concentrating and electrodecompartments at a flow rate of about 0.2 gpm, and applying a current ofabout 1 Amp. The flow rate to the diluting compartments was increased toa target of about 1.3 gpm, the current was increase to 2.0 Amps, and thefeed conductivity was 3.09 μS/cm. Under these conditions thesteady-state product water resistivity was found to be 11.2 MΩcm.

A second experiment was conducted in which the three dilutingcompartments were each filled with a patterned bound arrangement of dryDiaion strong acid and strong base ion exchange resin, in the sodium andchloride forms. The pattern used consisted of a first continuous phaseof about 147 g of dry bound anion exchange resin containing 72×1.9 cmcylindrical domains of second dispersed phase of about 123 g of boundcation exchange resin. The electrodeionization stack was firstregenerated by passing water to be purified at a flow rate of about 0.3gpm through the diluting compartments, passing water through theconcentrating and electrode compartments at a flow rate of about 0.1 gpmand applying a current of about 1 Amp. The flow rate to the dilutingcompartments was increased to the target of about 1.3 gpm, the currentwas increased to 2.0 Amps, and the feed conductivity was 2.74 μS/cm.Under these conditions the steady-state product water resistivity wasfound to be 17.88 MΩcm.

It will be understood, of course, that modifications can be made in theembodiments of the invention described herein without departing from thescope and purview of the invention as defined by the appended claims.

We claim:
 1. A porous and permeable ion exchanger containing cationexchange resin particles and anion exchange resin particles for use indeionizing a aqueous liquid comprising a porous and permeable continuousphase of one of cation exchange resin particles or anion exchange resinparticles and a porous and permeable dispersed phase of clusters of theother of the cation exchange resin particles or the anion exchange resinparticles in the continuous phase, in which the ion exchanger is in theform of a shallow bed having opposite planar bed surfaces, and in whichsaid dispersed phase clusters are conterminous with at least one of saidplanar bed surfaces.
 2. An ion exchanger as claimed in claim 1 in whichdispersed phase clusters extend through the shallow bed and areconterminous with the opposite planar bed surfaces of the bed.
 3. An ionexchanger as claimed in claims 2 in which the cation exchange resinparticles and the anion exchange resin particles are bound by a polymerbinder to form a cohesive bed.
 4. A method of producing a porous andpermeable ion exchanger as claimed in claim 3, die cutting a pluralityof shaped clusters of cation exchange resin particles or anion exchangeresin particles from a first sheet of said resin particles to form acontinuous phase of said ion exchange resin particles having a pluralityof holes therein, die cutting a plurality of identical clusters of theother of cation exchange resin particles or anion resin particles from asecond sheet of said resin particles, and fitting said cut-out clustersof the other of the cation exchange resin particles or anion resinparticles into the holes of the first sheet.
 5. An ion exchanger asclaimed in claim 1 in which the clusters are shallow cylinders orellipses.
 6. An ion exchanger as claimed in claim 1 in which theclusters are elongated cylinders or ellipses.
 7. An ion exchanger asclaimed in claim 1 in which the clusters are transversely multi-faceted.8. An ion exchanger as claimed in claim 1 in which the clusters have aright cylinder, right rectangle, right hexagonal or right multi-facetedprismatic shape.
 9. An ion exchanger as claimed in claim 1 in which atleast one of said dispersed phase clusters or the continuous phase haveembedded therein one or more shaped mesh preforms having a mesh sizesmaller than the average size of the resin particles, said preformshaving a right cylinder, right rectangles right hexagonal or rightmulti-faceted prismatic shape.
 10. An ion exchanger as claimed in claim1 in which at least one of said dispersed phase clusters or thecontinuous phase have embedded therein a honeycomb mesh having a meshsize smaller than the average size of the resin particles.
 11. An ionexchanger as claimed in claim 10 in which said honeycomb mesh has a cellwidth smaller than the width or diameter of the dispersed phaseclusters.
 12. An apparatus for demineralizing an aqueous liquidcomprising a demineralizing compartment having a cation exchangemembrane on one side of the compartment and an anion exchange membraneon the other side of the compartment and a porous and permeable bed of acontinuous phase of one of cation exchange resin particles or anionexchange resin particles and a porous and permeable dispersed phase ofclusters of the other of the cation exchange resin particles or theanion exchange resin particles within the continuous phase as claimed inclaim, said bed filling said compartment.
 13. An apparatus fordemineralizing an aqueous liquid comprising an anode compartment havingan anode and a cathode compartment having a cathode, and a plurality ofcation exchange membranes and anion exchange membranes which arealternately arranged between the anode compartment and the cathodecompartment to form demineralizing compartments each defined by an anionexchange membrane on the anode side and by a cation exchange membrane onthe cathode side, and concentrating compartments each defined by acation exchange membrane on the anode side and by an anion exchangemembrane on the cathode side, and a porous and permeable ion exchangeras claimed in claim 1 filling said demineralizing compartments.
 14. Amethod as claimed in claim 12 or 13, comprising the additional step oflocating a plurality of shaped mesh preforms having a mesh size smallerthan the average size of the resin particles in the receiving areadefining the continuous phase of the ion exchange resin particles.
 15. Amethod as claimed in claim 14, comprising the additional step offreezing said ion exchanger for transport.
 16. A method fordemineralizing water in an apparatus including an anode and a cathodecompartment having a cathode, and a plurality of cation exchangemembranes and anion exchange membranes which are alternately arrangedbetween the anode compartment and the cathode compartment to formdemineralizing compartments each defined by an anion exchange membraneon the anode side and by a cation exchange membrane on the cathode side,and concentrating compartments each defined by a cation exchangemembrane on the anode side and by an anion exchange membrane on thecathode side, and a porous and permeable ion exchanger as claimed inclaim 1 filling said demineralizing compartments, comprising feedingwater to be demineralized to said demineralizing compartments, flowingan electrical current between the cathode and the anode, and removingdemineralized water from the apparatus.
 17. A method of producing aporous and permeable ion exchanger as claimed in claim 1, whichcomprises positioning a template having a planar cover plate with aplurality of shaped, thin-walled hollow elements having open top andbottom ends depending downwardly therefrom over a designated receivingarea, and feeding an aqueous slurry of one of cation exchange resinparticles or anion exchange resin particles to said template to form acontinuous phase of said ion exchange resin particles, and feeding anaqueous slurry of the other of the cation exchange resin particles oranion exchange resin particles into the plurality of shaped, thin-walledhollow elements to form a plurality of dispersed phase clusters of theother of the cation exchange resin particles or the anion exchange resinparticles.
 18. A method as claimed in claim 17, comprising theadditional step of inserting a shaped mesh preform having a mesh sizesmaller than the particles size into the hollow elements.
 19. A methodas claimed in claim 18, comprising the additional step of freezing saidion exchanger for transport.
 20. A method of producing a porous andpermeable ion exchanger as claimed in claim 1, which comprisespositioning an array of dispensing nozzles for selectively dispensing anaqueous slurry of cation exchange resin particles or anion exchangeresin particles over a designated receiving area, and feeding to saiddesignated area an aqueous slurry of one of the cation exchange resinparticles or the anion exchange resin particles to form a continuousphase of said ion exchange resin particles, and feeding an aqueousslurry of the other of the cation exchange resin particles or anionexchange resin particles in a predetermined pattern to form a pluralityof dispersed discontinuous phase clusters of the other of the cationexchange resin particles or the anion exchange resin particles.
 21. Amethod as claimed in claim 20, comprising the additional step oflocating a shaped mesh preform having a mesh size smaller than theaverage size of the resin particles at the discrete discontinuous phaseclusters.
 22. A method as claimed in claim 21, comprising the additionalstep of freezing said ion exchanger for transport.
 23. A method asclaimed in claim 18 or 22, comprising the additional step of said shapedpreform having a right cylinder, or right rectangle, right hexagonal orright multi-faceted prismatic shape.
 24. A method as claimed in claim23, comprising the additional step of said shaped preform having a rightcylinder, or right rectangle, right hexagonal or right multi-facetedprismatic shape.
 25. A method as claimed in claim 24, comprising theadditional step of freezing said ion exchanger for transport.
 26. Amethod as claimed in claim 23, comprising the additional step offreezing said ion exchanger for transport.
 27. A method as claimed inclaim 17 or 20, comprising the additional step of forming said ionexchanger over an ion exchange membrane for intimate contact of thedispersed phase of ion exchange particles with the membrane.
 28. Amethod as claimed in claim 17 or 20, comprising the additional step offorming the ion exchanger in a spacer frame.
 29. A method as claimed inclaim 28, comprising the additional step of freezing said ion exchangerin the spacer frame.
 30. A method as claimed in claim 17 or 20,comprising the additional step of forming the ion exchanger in a jigover a film of supporting plastic for transfer to a spacer frame.
 31. Amethod as claimed in claim 30, comprising the additional step offreezing said ion exchanger in the jig for transfer of the ion exchangerto a spacer frame.
 32. A method as claimed in claim 17 or 20, comprisingthe additional step of selectively providing a honeycomb mesh in thereceiving area for incorporation in at least one of the dispersed phaseclusters or the continuous phase.
 33. A method as claimed in claim 32,comprising the additional step of freezing said ion exchanger fortransport.